1. Field of the Invention
The present invention relates to methods and apparatus for drying forage crops. More specifically, the present invention is a method and apparatus for cutting, drying and baling standing crops used for forage such as alfalfa and the like.
2. Discussion of Background and Prior Art
Forage crops such as alfalfa are harvested as many as five times in the growing season. The harvested crop has internal and external moisture, generally referred to as natural moisture, and, upon harvesting, may have sufficient excess natural moisture to cause the crop to rot or mold if not removed before the crop is stored. After the crop is mowed, it is left in the field to be sun-cured; that is, left in windows for a few hours or days depending on weather conditions and the natural moisture content of the crop until sufficiently dry for baling. When mowed, the crop stems are crimped to allow internal moisture to escape. While curing in the sun, the crop may be turned and fluffed to dry more evenly.
The loose crop is formed into bales that are typically either small and rectangular in shape or large round discs. It is stored in bales until use as food for livestock.
Rain or moisture from a heavy dew can spoil the windrowed crop or can result in spontaneous combustion if the crop is stored too wet. On the other hand, hot, dry weather can remove too much excess moisture, causing "shattering" as overly dry, brittle leaves and stems crumble during field handling. Therefore, careful timing of harvesting is essential to crop management so that as much of the crop is recovered with adequate but not excess moisture.
Crop management has been especially difficult in the southeast United States because of high temperatures and humidity and the frequency of summer thundershowers. Ideally, during the summer in the southeasern states, alfalfa and other forage crops should be baled as soon as the appropriate moisture content is reached.
Alfalfa is an especially good forage crop because of its high protein content, making it especially good for beef cattle, dairy cattle and horses. However, typically 10 to 15 percent by weight is lost because of repeated handling of the alfalfa for cutting, windrowing, turning and baling. An additional 20 to 30 percent by weight may be lost due to shattering or rain damage or both. Shattering is especially costly to the nutritional value of alfalfa because the leaves, rather than the less nutritive stems, are the first to be lost.
In addition to crop loss, there is also substantial investment in both time and energy made in repeated trips to the field for mowing, windrowing, turning and baling.
To minimize the time that crops lay in the field drying, certain acid preservatives are sometimes sprayed on the crop to allow crops having a higher moisture content to be baled and stored.
In addition to use of preservatives, there are numerous apparatus described in the prior art for drying a forage crop to lower levels of residual moisture, typically by the application of heat to the crop cuttings as they are fluffed and turned in a chamber within the apparatus. Frequently, rollers crimp the cut crop as it is cut to allow internal moisture to escape. Then heat energy is applied by a number of means such as open flames, sun lamps and microwaves.
For example, Van Der Lely, in U.S. Pat. No. 3,512,765, discloses an externally heated drum, positioned with its axis of rotation parallel to the direction of motion of the apparatus, the perimeter of the drum is fitted with an Archimedean screw conveyor to advance the crop. Winger, in U.S. Pat. No. 3,527,031 uses primarily microwaves, assisted by an internally heated roller, to dry crops.
The Van Der Lely invention and Rezabek's U.S. Pat. No. 2,806,554 use temperature sensed by a thermometer as a measure of the heat applied for drying but without measuring dryness directly or using the sensed temperature to control their respective apparatus.
The prior art does not disclose the use of heated rollers to press and evaporate internal and external, excess moisture from a cut forage crop so that it may be baled immediately. The prior art does not disclose the use of moisture detectors to control the temperature of the heated rollers and the speed of the apparatus in cutting the crop.